This invention relates to liquid fabric treating compositions capable of imparting softness to fabrics treated therewith, particularly in the rinse cycle of the laundering procedure, containing small amounts of di- and/or tri-valent metal soaps as the fabric softening agent.
Both textile processing and household laundering of fabrics require modifying agents to impart softness and pleasant feel of "hand" (smooth, pliable and fluffy) to the washed fabrics. The cationic, particularly the quaternary ammonium compounds are well known in the art as effective fabric softeners However, they have the disadvantages of causing yellowing of the fabrics treated therewith, and of complexing with the residual anionic detergent materials used in the washing cycle which decreases its efficacy as a softening agent. British Patent No. 1,456,913 and U.S. Pat. No. 3,920,565 have addressed these problems by providing a fabric softener composition comprising a mixture of a cationic fabric softener and an alkali metal soap which contributes to the softening function at low level usage.
U.S. Pat. No. 4,329,237 and No. 4,411,803 also discloses the combination of a water-soluble fatty acid soap and a quaternary softener as the softening agents in a detergent softener composition.
The prior art further discloses softening compositions containing a cationic softener, particularly the quaternary compounds, as the primary softening agent in combination with a modifying agent to improve its softening properties, as disclosed in U.S. Pat. No. 4,000,077, wherein the combination of a quaternary and an alcohol sulfate is used. U.S. Pat. No. 4,118,327 discloses the combination of a quaternary with a Phosphoric acid ester. U.S. Pat. No. 4,426,304 discloses the combination of a quaternary compound and a partially oxidized polyethylene or a fatty amphoteric compound as the softening agent. British Patent No. 1,408,787 discloses a combination of a quaternary compound and an oil or an alkyl ester of a long chain fatty acid. British Patent No. 1,576,326 and U.S. Pat. No. 4,139,479 disclose a textile treating rinse composition having softening properties comprising the combination of a cationic surfactant such as a quaternary compound and a water-insoluble soap.
Anionic fabric softeners are also known in the art and include soaps, sulfonated oils, sulfated castor oil, fatty alcohol sulfates and anionic emulsions of fats, oils or waxes 1 using soaps or fatty alcohol sulfates as emulsifiers, as disclosed in Soap/Cosmetics/Chemical Specialties for July, 1978, pp. 25-27. However, the anionics have limited durability, require higher treatment levels, are sensitive to water hardness (the calcium and magnesium in tap water), low pH and various electrolytes. These disadvantages have limited their use to textile processing applications. It is known that large amounts of sodium soap solutions of sodium or potassium soaps are added to tap water, a curd of calcium and magnesium soaps forms. This curd adheres to fabric and gives a soft hand which varies with the soap concentration. However, this curd is undesirably slimey and unsightly on the fabric, and the calcium soap in the curd are in the form of large particles. British Patent No. 1,329,416 discloses a particulate detergent composition having softening properties comprising a synthetic detergent active compound and 2-25% of a water-insoluble soap in the form of aggregate of particles of less than 2 microns. Water-insoluble soaps have also been used in conjunction with bentonite as the softening agent in a detergent softening composition or in a rinse cycle softening composition as disclosed in U.S. Pat. No. 4,436,637 and No. 4,472,287.
However, a liquid fabric softening composition consisting essentially of a predispersed, finely divided di- and/or tri- valent metal soap as an additive in the rinse cycle of the laundering operation is not disclosed.